Which two types of drill bits must be used to drill composite materials?

The use of carbide and polycrystalline diamond drill bits is essential for drilling composite materials due to their specific hardness and wear resistance properties. Composites, which often include layered fibrous materials like carbon or glass, require drill bits that can effectively cut through hard surfaces without causing delamination or significant damage to the surrounding material.

Carbide drill bits are extremely hard and maintain their cutting edges longer than other types, allowing for efficient drilling in tough composite substrates. Polycrystalline diamond bits, on the other hand, are even harder and are designed to withstand the abrasive nature of composite materials, providing a high-quality finish and reducing the risk of fiber pull-out or other common drilling issues. These characteristics make them the preferred choice for aviation and aerospace applications where precision and material integrity are paramount.

The other types of drill bits listed are generally not suitable for composite materials due to their lower hardness and inability to handle the specific challenges presented by composites. For example, high-speed steel is more suited for softer materials, while cobalt and carbon steel lack the hardness necessary for effective drilling in tougher materials. Diamond and ceramic bits, while hard, can be fragile and may not be viable for the types of drilling required in composite applications.